Metal Injection Molding (MIM)
Metal injection molding (MIM) is a process used to manufacture complex, high-precision metal parts, freeing designers from the traditional limitations of molding stainless steel, nickel iron, copper, titanium and other metals. The molding process combines metal powder, injection molding and sintering technology to ensure that MIM parts have tight tolerances and excellent surface quality.
Metal Injection Molding (MIM) Detailed Process
Material Mixing
The first step of the MIM process is to mix fine metal powder with a binder to form a homogeneous feedstock. This feedstock needs to have good flowability for subsequent injection molding. Precise control of this step directly affects the uniformity and performance of the final product.
Injection Molding
The mixed MIM feedstock is injected into the mold to form the initial part, called the "green body". The green body is usually slightly larger than the final product, which is to compensate for the inevitable shrinkage during the sintering process. Injection molding can efficiently produce parts with complex geometries, which is one of the core advantages of MIM technology.
Debinding
After molding, the green body needs to be debinded to remove most of the binder in the feedstock. This process produces an intermediate product called a "brown part". The brown part has a basic shape, but has low strength and requires further processing to achieve the final performance.
Sintering
Sintering is a key step in the MIM process. The residual binder is removed and the material is densified by heating the brown part to a temperature close to the melting point of the metal. The sintered part is close to the final size and has the required physical properties and mechanical strength. This process determines the final density and geometric accuracy of the product.
Post Processing
After sintering, additional secondary processing can be performed according to the specific requirements of the product, such as sizing to ensure dimensional accuracy, heat treatment to improve mechanical properties, or surface coating to enhance corrosion resistance and appearance. These additional processes ensure that MIM parts can meet stringent application requirements.
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Custom Projects Completed
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Advantages of MIM technology
High Volume Production
Suitable for producing large numbers of parts quickly and efficiently.
Reduced Material Waste
Minimum material waste due to the precision of the process.
Complex Geometries
Ability to create parts with complex shapes that are difficult or impossible to create using traditional methods.
Superior Performance
Parts produced through MIM have superior mechanical properties and durability.
Medical Industry
We use advanced MIM technology to produce precise and complex metal parts for the medical and dental industries, ensuring tight tolerances while supporting innovative designs. Our titanium alloy medical devices feature high strength-to-weight ratio, excellent biocompatibility and corrosion resistance.
With dimensional accuracy up to 0.001 mm and surface roughness of Ra 0.80~1.6μm after sintering, we provide lightweight, high-performance solutions that meet the demanding requirements of modern medical applications.
Optical Industry
Metal powder metallurgy is suitable for the manufacture of structural parts or auxiliary parts of optical parts, such as brackets, housings and heat dissipation components, but it is not suitable for the direct production of optical reflective or transmissive surfaces. For the production of optical core components, other processes (such as glass molding or precision cutting) are usually required.
Using specific metal powders (such as stainless steel, titanium alloy, etc.), MIM can achieve the strength, lightness and corrosion resistance required by optical devices.
Semicon Industry
MIM can produce small parts with complex shapes, and is particularly suitable for structural parts such as brackets, fixtures, and housings in semiconductor equipment, which usually have precise geometry and high strength requirements. It is also suitable for mass production and cost-effective for standardized parts in the semiconductor industry.
However, semiconductor parts usually require extremely low surface roughness (such as Ra 0.1~0.2μm) to prevent particle contamination. MIM parts require subsequent polishing or surface treatment to meet this requirement, which may increase costs.
3C Electronics Industry
The MIM process is very suitable for the manufacturing of small, complex and high-precision parts in the 3C electronics industry. It has significant advantages in mass production, lightweight and surface beauty, and is widely used in 3C products such as smartphones, smart wearable devices, and laptops. Card slots, buttons, brackets and other components.
However, parts with special performance requirements (such as high conductivity or extreme gloss) may need to be completed in combination with other processes.
Automotive Industry
Although CNC machining and die-casting still dominate the automotive industry, metal powder metallurgy (MIM) processes often have advantages for many small and complex parts. For example, key components such as remote control keys, blades, valves, connecting rods, valve guides and parking brakes are more suitable for manufacturing through MIM processes to achieve lightweight, complex geometry and excellent mechanical properties.
The high efficiency and quality stability of the MIM process in mass production enable it to meet the automotive industry's stringent requirements for high precision, high strength and wear resistance. With its flexible adaptability to various alloys and customized formulations, MIM provides manufacturers with greater design freedom, helping innovative parts quickly pass the production part approval process (PPAP) and accelerate the development and launch of new models.
Metal Injection Molding FAQ's
What is Metal Injection Molding (MIM)?
MIM is a manufacturing process combining powder metallurgy and plastic injection molding, ideal for producing complex metal parts with high precision.
What materials are used in MIM?
Common materials include stainless steel, low-alloy steel, titanium, tungsten alloys, and other specialty metals.
Is MIM cost-effective for small production runs?
MIM is most cost-effective for high-volume production but can be viable for smaller runs with complex designs.
What is the typical lead time for MIM parts?
Lead times range from 4–8 weeks, depending on the part's complexity and volume.
What part sizes are suitable for MIM?
MIM is best for small parts, typically weighing 0.1 to 100 grams, though larger parts may also be feasible.